Communication system



June 5, 1945. R. H. CAMPBELL COMMUNICATION SYSTEM Filed Aug. 27, 1943 3 Sheets-Sheet 1 fifg June 5, 1945.

R. H. CAMPBELL COMMUNICATION SYSTEM Filed Aug. 27, 1943 3 Sheets-Sheet 2 A0 War-r June 5, 1945. R. H. CAMPBELL 2,377,672

\ COMMUNICATION SYSTEM Filed Aug. 27, 1943 I 3 Sheets-Skeet 3 Patented June 1945 UNITED STATES PATENT OFFICE COMMUNICATION SYSTEM Richard H. Campbell, Racine, Wia, allignor to Webster Electric Company, Racine,

poration of Delaware Application August 27, 1943, Serial No. 500,205

13 Claims.

The present invention relates to communication systems, and particularly to loudspeaking in:- tercommunication systems.

'An object of the present invention is to provide an lntercommunicating system wherein one or tives stations for showing when the apparatus thereat is conditioned for the transfer of calls to the secretary's station.

A further object of the present invention is to provide an arrangement of the character specified wherein the secretary can call the executive at any time.

Other objects and advantages of the present invention will become apparent from the ensuing description, in the course of which reference is bad to the accompanying drawings, in which:

Fig. 1 is a diagrammatic representation of an embodiment of the invention in a communicating system of the character wherein communication is carried on in alternate directions between stations by the alternate manipulation of communication direction control switches thereat; and

Figs. 2 and 3 are diagrammatic representations of modified'embodiments of the invention.

Referring now to Fig. 1, it may be noted that the system is of the multiple station type including four stations indicated by reference characters I to 4, inclusive. In order better to describe the operation and advantages of the invention, the system has been illustrated as including an executives station I, a subexecutives station 4, a substation 2, and a secretary's station 3.

Wia, a corand to an incoming communication circuit 20 to which the loudspeaker is connected through an adjustable volume control potentiometer 22.

In one position, the listen position, of the switch I6, the loudspeaker I3 is connected to the incoming circuit through the switch blades 24', and in the other position, the talk position, the loudspeaker is connected to the input of the amplifier through circuit I2. In the listen position the output circuit is shorted by switch blade 26, and in Y the talk position the amplifier output is connected through the switch blade 20 to an output circuit 28.

go switch blade 34. Whenever the amplifier is in use.

The amplifier is supplied with power through a power supply line 30. The communication direction control switch It is utilized also to cut ofithe amplifier plate voltage in the listen position of the switch. In the talk position the plate voltage circuit is completed through conductors '32 by the tubes are conditioned to be rendered immediately operative upon completion of the plate voltage circuit. Each 01 the stations in the system has its indi- 25 vidualincoming circuit, which may be termed Much of the apparatus included at all four I amplifier input and output connections, and also the connection of a loudspeaker I8 ofthe permanent m its "home line. The home lines for stations I, 2, 3, and 4 are indicated by reference characters H, 42, 43 and 44, respectively. I

Each station is provided with station selector switches in its output circuit 28 whereby that circuit can be connected to the home lines of the other stations. Thus, station I is provided with station selector switches 45, 48 and 50 individual to stations 2, 3 and 4, respectively; station 2 is provided with selector switches 52, 54 and 56 individual to stations I. .3 and 4, respectively; station 3 is provided with selector switches 58, 60 and 62 individual to stations I, 2 and '4, respectively; and station 4 is provided with station selector switches 64, 68 and 63 individual to stations I, 2 and 3, respectively.

The executive and subexecutive stations I and 4, respectively, are provided with switch means and are so connected with circuits leading to the secretary's station 3 that incoming calls to them may be'transferred to the secretary's station. Thus, the'stations I and 4 are provided with transfer switches 10 and 12 whereby the home lines 4| and 44 individual to stations I and 4 can be connected to the home line 43 individual to station 3. In the indicated position of switch 10 at station I, the station I home line H is connected to the incoming circuit 20 of station I. In its other position switch 10 connects home line H to et type to the input of the amplifier home line 43. of station 3. In similar manner.

1 T the switch I2 at station 4 connects the station 4 home line circuit 44 to the incoming'circuit 20 at the station in one position, and in its other position the station 4 home line 44 is connected to station 3 home line 43.

In order that an indication be given at, the executives and subexecutive's stations of the transfer of incoming calls to the secretary's station, there are provided indicator lights I4 and I3 at the two stations. These are adapted to be supplied with power from a suitable source (not shown) whenever the switches I and I2 are operated to transfer calls to the secretary's station. when the switches have been so operated, energizing circuits for the lamps are completed through switch blades I8 and80 operating simultaneously with switches I0 and I2.

Another feature of the present invention resides in the provision of a circuit whereby the secretary may communicate with the executive at any time. The circuit includes the conductors 82 leading from selector switch 58 at station 3 to the incoming circuit at station I. Thus the secretary station may communicate with the executive station, no matter what the position of the transfer switch I0.

In describing the operation of the system it is assumed all the amplifiers III are supplied with power and conditioned for immediate operation upon actuation of switches I6 into thei talk positions. Undernormal conditions the switches are in their idle positions so that the loudspeakers I8 at the stations are connected to their individual home lines ready for the reception of calls from other stations.

It is. assumed first that station 2 desires to communicate. with station I. The operator at station 2 first closes selector switch 52, thereby connecting the output circuit 28 at station 2 to interstation circuit 4I individual to station I. Switch I6 at station 2 is then operated to its talk position, at which time the loudspeaker I8 is connected to the input of amplifier I0 through circuit I2 and the output of the amplifier is connected to circuit 28 through circuit I4. Thus station 2 is conditioned for transmission to station I through the amplifier at station 2 and circuit 4I. .After the call has been made the operator at station 2 releases the switch I6 thereat, thereby to condition the station for reception. To answer, the operator at station I first closes station selector switch 46 and then operates switch I6 to condition the station for transmission through the amplifier Ill and through interstation circuit 42 individual to station I. Thereafter, communication may be carried on in opposite directions by alternate operation of the switches I 6 at the two stations.

Stations I, 2 and 4 may communicate with each other in the same manner as stations I and 2, and it is believed that further description of the manner in which this is done is not necessary. I

In the event the operator at station I, who, as heretofore indicated, may be an executive, leaves his oflice or does not desire to answer calls, he

may operate switch III to transfer calls to station 3. When the switch III is operated the circuit 4I individual to station I is connected to the circuit 43 individual to station 3, and the. operator at station 3 receives calls directed to station I. In addition, the operator at station 3 receivescalls directed to it over the interstation circuit 43 in the same manner as the other stationsin the system. In the event the operator at station 3 receives a call, an answer can be made upon closure of the station selector switch corresponding the calling station and manipulation of coinmunication direction control switch I6.

Station 3 can communicate with station I at all times, i. e.. even when the transfer switch I0 has been operated at station I.' Assuming that the switch ID has been operated to transfer calls to station 3, yet station 3 can call station I. To

do this, the operator at station 3 closes selector switch 58, thereby connecting the station 3 output circuit 28 to the loudspeaker I8 at station I through the interstation circuit 32, reception circuit III at station I, the potentiometer 22, and the switch blades 24. n the operator at station I should be present to receive the call, then answer can be eflfected simply by closure of station selector switch 48 corresponding to station 3 and operation of switch I6 intoits talk position, assuming, of course, that the operator at station 3 has released switch I6 thereat.

The operator at station 4 may similarly transfer calls to station 3 upon operation of the selector switch I2 thereat to connect interstation circuit 44 corresponding to station 4 to interstation circuit 43 corresponding to station 3. Station 3 can, however, call station 4 only in the ordinary manner; that is, through the interstation circuit 44 individual to station 4. Thus station 3 cannot communicate with station 4 when the transfer switch I2 has been operated. However. if desired, station 4 could be connected to station 3 in the sameway as station I, so that station 3 could call station 4 at any time.

The operators at the executive and subexecue tive stations I and 4 are given an indication that incoming calls are being directed to the secretarys'station by the indicator lights I4 and I5 which are energized when the transfer switches III and 12 are operated to transfer calls.

.40 The present invention may be applied to other types of systems, and in Fig. 2 it is shown applied to a system of the type wherein each of the stations is provided with an amplifier to the input of which is connected a microphone, and with a loudspeaker utilized only for reception. Th apparatus at each station may be of the type disclosed and claimed in my Patent No. 2,323,307. granted July 6, 1943.

The system of Fig. 2 is quite similar to that of Fig. 1, and like elements have been indicated by like reference characters. The system is characterized by interstation circuits individual to the various stations to which the loudspeakers I8 are normally connected, and by amplifiers III having their outputs connected to output circuits 28 leading to the station selector switches individual to the other stations and microphones I00 connected to their inputs. The amplifiers are norreception volume is controlled by switch blade I04 adapted normally to short circuit resistor I06 in series with the loudspeaker and adaptedin operated position to remove the short circuit and to place a resistor I08 in parallel with the voice ,coil of the loudspeaker. -The' amplifier gain is controlled by switch blade IIII adapted inoperated position of the switch to decrease the gain of the amplifi The operation of the system shown in Fig. 2 is very similar to that of Fig. '1. In brief, one

station may call another upon closure of theselector switch corresponding to the other station. For instance, station 2 may call station I upon closure of selector switch 62, thereby to connect loudspeaker I8 at station I to the output of amplifier I at station 2. To reply. the operator at station I closesselector switch 46, thereby to connect the amplifier at station I to the loudspeaker I8 at station 2. Thereafter communication may be carried on between the two stations without any further operationiof switches. In order for one station to transmitto anotherat higher volume, the high volume switch I02 at the station may be operated, thereby to increase the tion 3. Thus any calls directed to station I are received at station 3, and the operator at station 3 can answer upon closure of the proper station selector switch-which would beswitch 60 for station I. In similar manner, the operator at station 4 may direct calls directedto it, to station 3.

The operator at station 3- may communicate with station I at-all times-even when the transfer switch has been operated. This results from the connection of circuit 82 tocircuit at utilized if desired.

Each of the stations is normally conditioned for the reception of calls from other stations by its communication direction control switch I20 comprising a pair of switch blades I22 and I24. In the listen position of the switch the loudspeaker I8 is conditioned for reception of calls through the amplifiers at other stationsby a circuit including both switch blades I22 and m and the communication circuit I26. In th talk position of the switch the station is conditioned for transmission through its own amplifier, the loud-' speaker I8 being connected to the input through switch I22 and the circuit I26 being connected to th output through switch blade I24.

The stations are connected by a number of interstationcircuits I3I, I32 and I33 individual to the stations I, 2 and 3 of the system. The stations also include station selectorswitches normally connecting the circuits I26 thereat to their individual interstation circuits and operable tointerconnects circuits I26 3 selector switch I88 and Ill.

In this embodiment of the invention only station I has been provided with switch means for transferring calls directed to it to station. 3. This transfer switch means is indicated by reference character I40, and it normally closes the circuit I26. When it is desired to transfer calls the switch is operated to another position to connect selector switch I34 (and also circuit I3I individual to station I) to the interstation circuit I33 individual to station 3. Accordingly, any calls directed to station I are transferred to station 3.

Station 3 may call station I atany time, even though the transfer switch I40 at station I has been operated. This results from interconnecting stations I and 3 by a circuit I through which the circuits I26 at the two stations may be directly connected upon operation of the station selector switch I38 at station 3.

Reviewing the operation of this system, one station may call another by operation of the selector switch to select the desired station, and upon operation of the communication direction control switch I24 to condition the station for I transmission. Thus station 2 may call station I by the transfer switch I40 at station I.

connect circuits I26 to the circuits individual to I26 and I3I; at station 2 the selector switch I36 interconnects circuits I26 and I32; and at station operating selector switch I36 to complete acircuit to circuit I3I individual to station I and by operating switch I24 to its lowermost position. When these operations 'have been completed, loudspeaker I8 at station 2 is connected to the input of the amplifier I0 at the station and the loudspeaker I8 at station I is connected to the output of the amplifier through the interstation circuit I3I, the selector switches I34 and. I36, and

T0 condition the circuits for a. reply from station I, the operator at station 2 releases switch I20 and the operator at station I operates the switch I20 thereat to its talk position. When this is done,

the loudspeaker I8 at station I is connected to the input of amplifier I0.at the station and the output of the amplifier is connected to the loudspeaker I8 at station 2.-

If the operator at station I desires to transfer incoming calls to station 3, it is necessary only to operate the transfer switch I40 to connect the interstation circuit I3I individual to station I to the interstation circuit I33 individual to station 3. Calls directed to station I are thereupon transfIerred to station 3 and communication may "thereafter be held between the calling station,

and station 3 the same as heretofore described in connection with communication-between stations l and 2.

Station 3 may communicate with station I at i any time even though transfer switch I40 at the latter has been operated. When station 3 desires to communicate with station I, the selector switch I38 is operated to interconnect circuits I26 and MI and the communication direction control switch I20 at station 3 is operated to its talk position. Loudspeaker I8 at station 3 is thus connected to the input of amplifier III at station 3 and the output of the amplifier is connected to loudspeaker I8 at station I. To condition the circuits for answer by station I, the

communication direction control. switch at station 3 is released and the switch atstation I is operated to its talk position.

Although the invention has been described in connection with specific details of preferred embodiments thereof, it should be understood that such details are not intended to be limitative of the invention except in so far as stated in the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent of the United States is:

1. In a communication system, the combination including, a first station having a loudspeaking receiver and an interstation communication circuit individual thereto to which said receiver is connected to reception, 9. second stacombination including, a. first station having switch means normally completing its reception circuit, and means including said switch means at the first station and a-circuit controlled thereby for connecting the first station interstation reception circuit to the reception circuit of a second station.

3. In a communication system, the combination including, a first station having an inter.-

station communication circuit individual thereto and communication direction control switch means for. conditioning the circuit for reception thereover, a second station normally conditioned for reception, and means including switch means at the first station normally connecting said first station to its interstation circuit and a circuit between said first and second stations controlled by said switch means for transferring calls directed to the first station to the second station.

4. In a communication system, the combination including, a first station having a loudspeaking receiver and an interstation reception circuit individual thereto to which the receiver is connected, a second station normally conditioned for reception, and means including switch means at the first station in circuit with said receiver and normally connecting the receiver to said interstation circuit and a circuit between said first and second stations controlled by said switch means for connecting said reception circuit to the second station.

5. In a communication system, the combination including, a first station having a loudspeaking receiver and an interstation reception circuit individual thereto and communication direction control switch means for connecting the receiver to the circuit for reception thereover, a second station normally conditioned for reception, and means including switch means at the first station normally connecting said receiver to its interstation circuit and a circuit betweensaid first-and second stations controlled by said switch means for connecting said reception circuit to the second station.

6..In a communication system, the combination including, a first station having a loudspeaking receiver and an interstation circuit individual thereto over which communication is carried on alternately in opposite directions and communication direction control switch means for conditioning the station for reception or transmission over said circuit and normally connecting the receiver to said circuit-for reception, .9. second station normally conditioned for reception, and means including switch means at the first station normally connecting said receiver to its interstation circuit through said communication direction control switch and a circuit between said first and second stations controlled by said switch means for connecting said interstation circuit to the second station.

7. In a communication system, the combination including, a first station having'an interstation communication circuit, a second station, 7

means including switch means at the first station normally connecting said first station to said interstation circuit and a circuit between said first and second stations controlled by said switch means for connecting said interstation circuit to said second station, and means including another circuit between said stations for enabling the second station to communicate with the first irrespective of the position of said switch.

8. In a communication system, the combination including, a first station having a loudspeaking receiver and an interstation communication circuit to which the receiver is connected, a second station having receiving and transmite ting means, means including a switch means at the first station normally connecting said receiver to said interstation circuit and a circuit between said first and second stations controlled by said switch means for connecting said interstation circuit to the receiving means at said second station, and means including another circuit between said stations for placing the transmitting means at the second station in circuit with the receiving means at the first station irrespective of the position of said switch means. 9. In a plural station communication system of the loudspeaking type wherein communication is carried on alternately in opposite directions over separate interstation circuits under the control of communication direction control switches at the stations, the combination including, a

multi-position switch at one station completing the reception circuit for said station in one position, means including a circuit between said one station and the reception circuit for another station adapted to be com leted by said switch in another position for transferring calls directed to the first station to the second station, and means including a circuit from the second station to the station side of the reception circuit at the first station for enabling the second station to communicate with the first station irrespective of the position of said multi-position switch. g

10. In a plural station communication system of the loudspeaking type wherein communication is carried on alternately in opposite directions over separate interstation circuits, one of which includes a loudspeaking receiver, the-combination including,-a multi-position switch at one station connecting the receiver to said one interstation circuit in one position, means including a circuit between said one station and the reception circuit for another station adapted to be completed by said switch in another position for transferring calls directed to the first station to the second station, and means including a, circuit from the second station to said receiver for en,- abling the second station to communicate with the first station irrespective of the position of said multi-position switch.

11. In a plural station communication system of the loudspeaking type wherein communication is carried on alternately in opposite directions over a single interstation circuit under the conto be completed by said switch in another position for transferring calls directed to the first station to the second station, and means including a circuit from the second station to said receiver for enabling the second station to communicate with the first station irrespective of the position of said multi-position switch.

12. In a communication system, the combination including, a first station having an interstation communication circuit, a second, station, means including a switch means at the first station normally connecting said first stationto said interstation circuit and a circuit between said first and second stations controlled by said switch means for connecting said interstation circuit to said second station, and signal means at said first station controlled in response to the position of said switch means for indicating the condition of said switch means.

13. In a communication system, the combination including, a first station having an inter station communication circuit, a second station,

means including a switch means at the first station normally connecting said firststation to said interstation circuit and a circuit between said first and' second stations controlled by said switch means for connecting said interstation circuit to said second station, signal means at said first station, and switch means controlling said signal means operable simultaneously with said first mentioned switch means for indicating the condition of said switch means.

RICHARD H. CAMPBELL. 

